It may be desirable to shape cover fabrics for vehicle seats and carpets made of knitted or woven fabrics to be used on the floor within the vehicle into three-dimensional configurations such as certain undulations. FIGS. 1 and 2 illustrate certain of such examples. In FIG. 1, a carpet to be used on a floor in front of the front seat of the vehicle is shown in perspective view. The floor of the vehicle presents rather complex undulations dependent upon the type of vehicle. As the carpets to be used on such floors are to be fitted to such undulations, it is desirable to preliminarily shape these carpets into corresponding three-dimensional configurations. A carpet 50 shown in FIG. 1 has been shaped into a configuration having a relatively flat portions 52, low raised portions 53 between adjacent flat portions 52, and a central raised portion or hump 54. Central raised portion 54 is provided with an opening 55 for receiving any shift lever or the like. Any backing materials such as, usually, polyurethane foams can be applied to the rear surface of such carpets by a variety of methods as hereinbelow described.
Another example of cover materials shaped into desired three-dimensional configurations is a seat cover 60 shown in FIG. 2. Cover 60 has raised side portions and a depressed central portion. Each side portion is comprised respectively of an outside wall 62, a top portion 63 and an inside wall 64 which is connected at its lowest end to the depressed central portion 65 by a narrow groove 67. If cover 60 is shaped into and maintained in these configurations, it would be easier to manufacture seats molded integrally with cover by pouring foamable mixtures such as a liquid polyurethane mixture into such shaped cover and allowing the mixture to expand and foam in situ. Various attempts have heretofore been made to shape cover materials into such three-dimensional covers.
One of such attempts is a method to make false creases in the cover fabric by confining the fabric between upper and lower molds which each have required surface configurations or undulations, then compressing the fabric by closing the molds, and, after opening the upper mold, applying and adhering paddings (foamed materials) onto the cover fabric held on the lower mold into desired configurations to obtain a cover material shaped into three-dimensional configurations maintained by the paddings.
However, it is difficult to obtain sharp and deeply drawn shapes in the cover fabric by this method unless paddings are adhered to the fabric because the fabric is only subjected forcibly to a mere compression between the mold surfaces to make creases that simulate hidden stitching. These creases will easily be lost upon removal of the cover fabric without paddings from the molds. Thus, this method cannot be considered to be a method for shaping the cover fabric in a strict sense, and has disadvantageously limited applications.
A second type of the prior art method comprises preparing a laminated cover material composed of woven or knitted fabric and a slab polyurethane layer attached to the rear surface thereof by means of flamewelding technique or adhesives, compressing such cover material in a shaping mold heated to a temperature ranging from 150.degree. to 170.degree. C. to crush and deform permanently the polyurethane layer thereby to obtain a shaped cover material. This second type of method, however, has many disadvantages. First, crushing and deforming the slab polyurethane which is a cured thermoset foam requires high temperature such as 150.degree. C.-170.degree. C. and high pressure in the range of about 8 to 10 kg/cm.sup.2 to be applied to the cover materials as well as requiring the compression to be maintained for a long period of time. Second, since high temperature and pressure are applied in the process of shaping, the cover material employable in this method is disadvantageously limited to textile materials, and other materials such as vinyls and leather cannot be used because of the possibility of damages caused by high temperature and pressure. Third, selection of the textile materials is limited to a rather narrow range of particular items, namely, for example, polyester fibers can be used satisfactorily whereas nylon and acrylic fibers having low melting points cannot be suited to this method. Even with polyester fibers, high temperature and pressure may cause such defects as falling down of piles of the fabric, and uneven appearance of the fabric surface to occur. Fourth, many complicated and time-consuming steps are required in this method in that to make slab polyurethane, a large block of foamed polyurethane must first be molded, then slicing the block into a plurality of thin polyurethane slabs is required, and then combining the slab polyurethane with the cover fabric is performed to obtain the laminated and composite cover material before the compressing operation is initiated. In addition, slab polyurethanes have varied degrees of stiffness and thickness and thus do not have much flexibility in designing articles utilizing such composite cover materials. Moreover, serious defects are noted in this method in that flame-welding or laminating of slab polyurethanes to cover fabrics causes noxious gases.
A third method, similar in part to the above-mentioned second method involves preparing a threefold cover material composed of the cover fabric, slab polyurethane and urethane film, and heating the composite material to approximately 150.degree. C., shaping the material into desired configurations by means of a vacuum, pouring foamable mixtures directly into the shaped cover material thereby to yield an integrally molded article. This method, however, has a disadvantage in that, in order for the cover material to follow the mold surface with high fidelity before pouring a liquid foamable mixture, vacuum apparatus with excessive investment is required. In addition, this method is not applicable to shaping the cover material in general and has limited applications.
Finally, it is also known to heat cover materials with thermoplastic olefinic resin backings to 100.degree.-150.degree. C., place such cover materials in a mold having upper and lower halves to deform permanently resin backings into desired shapes. Resin backings used in this method, however, are generally stiff in nature and thus result in rather stiffened cover materials which are not suited to general purposes.
On the other hand, U.S. Pat. Nos. 3,506,600 and 3,650,993 both to Natale C. Zocco et al. disclose densified polyurethane foams useful as backings for floor covering materials and a process for preparing the same. The Zocco patents disclose that the densified polyurethane foams can be prepared by applying a compressive force to a partially cured cellular material to reduce its volume by a specified amount. Also, the Zocco patents disclose, as a modified process, that the densified polyurethane composition may be formed by pouring the foamable mixture directly onto the back of a floor covering such as tiles, carpets and the like, and compressing the resulting partially cured cellular material to form a densified polyurethane composition. The densified polyurethane composition made by the Zocco patents has a densified core in the middle zone of foam and has a low density porous composition adjacent the exterior surfaces. The Zocco patents state that the latter may be retained as part of the backing of the floor covering.
However, the Zocco patents do not disclose or suggest in any way that a cover material could be shaped into three-dimensional configurations. The cover material obtained by Zocco is essentially flat in combined form with the backing, so these patents are not relevant to shaping of the covering materials.
Slab stock foam has previously been compressed to provide greater strength such as for carpet padding, to control size of cells such as for use as a filtering media, and to provide localized compressed areas such as for reinforcement for fasteners. Such prior art and other foam prior art noted during investigation conducted for the present invention are disclosed by U.S. Pat. Nos.: 3,342,485, Griffen; 3,622,435 Cacella; 3,709,966 Gambardella; 3,867,320 Gambardella et al.; 3,880,977 Gealer et al.; 3,978,266 Lock; 3,978,855 McRae et al.; 4,180,631 Yukuta et al.; 4,228,076 Pettingell; 4,241,189 Sheldon et al.; 4,246,361 Yukuta et al.; 4,265,965, Chancler; 4,278,482, Poteet et al.; 4,304,810 Gates et al.; 4,443,286 Ikeda et al.; 4,465,388 Iwasawa; 4,508,774 Grabhoefer et al.; 4,513,518 Jalbert et al.; 4,515,646 Walker et al.; 4,600,461, Guy; 4,656,906 Mozieka et al.; 4,668,557 Lakes; 4,740,256 Vosberg; 4,781,774, Steward et al.; 4,789,584, Perrin; 4,810,316, Wakabayashi et al.; 4,816,494 Watson, Jr. et al.; 4,828,238 Mozieka et al.; 4,850,579 Fisher; 4,878,972, Kaneko et al.; and 5,032,622 Herrington et al.